1. Field of the Invention
The present invention relates to a method of lapping a medium-opposing surface in a thin-film magnetic head.
2. Related Background Art
In general, a head gimbal assembly (HGA) is constructed by attaching a head slider formed with a thin-film magnetic head to a leading end of a flexible arm member such as a suspension. This head gimbal assembly is built into a hard disk drive and carries out recording/reproducing with respect to a hard disk which is a recording medium. At the time of recording/reproducing, an airflow accompanying the rotation of the hard disk occurs under the thin-film magnetic head, thereby levitating the thin-film magnetic head. As the hard disk attains a higher density, the gap between the thin-film magnetic head and hard disk, i.e., head flying height, has been decreasing to 10 nm, which currently seems to be the limit.
Under such circumstances, in a combination thin-film magnetic head in which a magnetoresistive device for reproducing and an inductive electromagnetic transducer for writing are laminated in this order on a support, a coil constituting the electromagnetic transducer will generate heat when the inductive electromagnetic transducer is energized. Then, the thin-film magnetic head will thermally expand in the vicinity of the electromagnetic transducer in a surface opposing a recording surface of the hard disk in the thin-film magnetic head, i.e., medium-opposing surface (ABS; Air Bearing Surface), thereby projecting toward the hard disk. As a consequence, the gap between the thin-film magnetic head and hard disk may decrease, thereby causing the thin-film magnetic head and hard disk to crush against each other. Therefore, the flying height of the thin-film magnetic head must be kept such that the thin-film magnetic head and hard disk do not crush against each other even when the vicinity of the electromagnetic transducer thermally expands. Hence, it has been difficult for the thin-film magnetic head to fully achieve low levitation.
Known as examples of techniques for achieving lower levitation of the thin-film magnetic head by preventing such a state from happening include one in which the leading end part of an overcoat layer on the medium-opposing surface side in the thin-film magnetic head is partly shaved to yield a step, and one in which the glass transition temperature of a coil constituting the electromagnetic transducer is set to about 70 to 100° C., so as to lower the Young's modulus, thereby reducing the thermal stress occurring in the coil part (see, for example, Japanese Patent Application Laid-Open No. 2000-306215).